The field of the invention is machine elements and mechanisms, particularly control lever and linkage systems having multiple controlling elements.
The present invention is particularly concerned with a drive for the compound stage of a microscope, or a similar apparatus displaceable along two coordinates in rectilinear guides, with a release device for the drive to rapidly adjust the carriage.
Applicant incorporates herein the disclosure of his U.S. Pat. No. 4,552,033 which shows the state of the art of drive systems for microscope stages or the like.
The present invention begins with a state of art such as is disclosed by U.S. Pat. No. 4,552,033. This patent discloses a position control in which the drive connections between the actuating knobs and the stage consist of a frictional linkage with friction wheel and friction track. In order to allow rapid displacement of the stage, the friction wheels are lifted off their associated friction tracks by pins acting on them in the axial direction of the drive shafts, whereby the stage is freely displaceable.
However, this type of stage displacement incurs the drawback that the force exerted by the pins in the axial direction of the shafts may slightly affect the set height of the stage, i.e., to change this height. As a result, the focus of the object underneath the microscope objective is lost. Frequently, refocusing is then required.
West German patent application No. P 35 05 217 filed Feb. 15, 1985 and not yet part of the state of the art discloses a position control for a compound slide displaceable in two straight guides along two coordinates for a microscope or similar apparatus. The apparatus has one drive link between the first slide and the stationary stage part and one drive link between the first and the second slides, the position-control consisting of two shafts supported in coaxial manner, with one actuation knob mounted at each end of each shaft, and the drive link consisting of two pinions, each fixed to one of the two shafts and meshing with a gear rack at the stationary stage part and at the second slide respectively.
One brake shoe each is provided for each shaft and is movable into an OPEN and into a BRAKED position, where each shoe in the OPEN position releases its associated shaft so as to allow easy shaft rotation and where in the BRAKED position the shoe brakes this shaft into a rotation against resistance. One clamping element each is provided for each brake shoe and this clamping element is transferable by an actuation means resting on the first slide into a position respectively closing and opening the brake shoes.
The shafts are supported by ball bearings assuring especially easy rotation of the shafts in the OPEN position.
The brake shoes are inherently elastic springs cut open at one location of their circumference, each one being slipped over a shaft and the clamping elements assuming a U-shape and being displaceable approximately perpendicularly to the shafts and thereby compressing or releasing the slitted rings by their U-shaped legs.
Application P 35 05 217 contains braking jaws in the form of slit rings being compressed by clamping elements displaceable in the direction of the axis of the coaxial shafts. The U-shaped legs of the clamping elements rest almost laterally against the rings outside the plane of the center axis of the coaxial shafts. One component of force is obtained in this clamping process at each clamping site, and all these components cooperatively act in the direction of the displacement of the clamping elements on the shafts, whereby these shafts are forced to the rear. While the lateral offset of the coaxial shafts is minimal, it is nevertheless noticeable at large microscope amplifications as a displacement of the object in the image field of the objective.